diff --git a/make/hotspot/lib/CompileJvm.gmk b/make/hotspot/lib/CompileJvm.gmk
index 6b5edc85b2369..687b05002dadd 100644
--- a/make/hotspot/lib/CompileJvm.gmk
+++ b/make/hotspot/lib/CompileJvm.gmk
@@ -188,20 +188,16 @@ $(eval $(call SetupJdkLibrary, BUILD_LIBJVM, \
     DISABLED_WARNINGS_gcc_cgroupV1Subsystem_linux.cpp := address, \
     DISABLED_WARNINGS_gcc_cgroupV2Subsystem_linux.cpp := address, \
     DISABLED_WARNINGS_gcc_g1FreeIdSet.cpp := unused-const-variable, \
-    DISABLED_WARNINGS_gcc_handshake.cpp := stringop-overflow, \
     DISABLED_WARNINGS_gcc_interp_masm_x86.cpp := uninitialized, \
     DISABLED_WARNINGS_gcc_javaClasses.cpp := unused-const-variable, \
     DISABLED_WARNINGS_gcc_jfrChunkWriter.cpp := unused-const-variable, \
     DISABLED_WARNINGS_gcc_jfrMemorySizer.cpp := unused-const-variable, \
     DISABLED_WARNINGS_gcc_jfrTraceIdKlassQueue.cpp := unused-const-variable, \
-    DISABLED_WARNINGS_gcc_jvmciCodeInstaller.cpp := stringop-overflow, \
     DISABLED_WARNINGS_gcc_jvmFlag.cpp := unused-const-variable, \
-    DISABLED_WARNINGS_gcc_jvmtiTagMap.cpp := stringop-overflow, \
     DISABLED_WARNINGS_gcc_macroAssembler_ppc_sha.cpp := unused-const-variable, \
     DISABLED_WARNINGS_gcc_postaloc.cpp := address, \
     DISABLED_WARNINGS_gcc_shenandoahLock.cpp := stringop-overflow, \
     DISABLED_WARNINGS_gcc_stubGenerator_s390.cpp := unused-const-variable, \
-    DISABLED_WARNINGS_gcc_synchronizer.cpp := stringop-overflow, \
     DISABLED_WARNINGS_gcc_templateInterpreterGenerator_x86.cpp := unused-const-variable, \
     DISABLED_WARNINGS_gcc_xGlobals_ppc.cpp := unused-const-variable, \
     DISABLED_WARNINGS_clang := $(DISABLED_WARNINGS_clang), \
diff --git a/src/hotspot/share/jvmci/jvmciCodeInstaller.cpp b/src/hotspot/share/jvmci/jvmciCodeInstaller.cpp
index 3a9fbc54bf941..a6433d28d9ba4 100644
--- a/src/hotspot/share/jvmci/jvmciCodeInstaller.cpp
+++ b/src/hotspot/share/jvmci/jvmciCodeInstaller.cpp
@@ -923,6 +923,17 @@ int CodeInstaller::estimate_stubs_size(HotSpotCompiledCodeStream* stream, JVMCI_
 // perform data and call relocation on the CodeBuffer
 JVMCI::CodeInstallResult CodeInstaller::initialize_buffer(JVMCIObject compiled_code, CodeBuffer& buffer, HotSpotCompiledCodeStream* stream, u1 code_flags, JVMCI_TRAPS) {
   JavaThread* thread = stream->thread();
+#if defined(__GNUC__) && !defined(__clang__) && !defined(PRODUCT)
+  if (thread == nullptr) {
+    // This is to prevent --stringop-overflow warning from GCC on linux/fastdebug.
+    // GCC does believe that JavaThread::current() can return nullptr,
+    // though it cannot.
+    // GCC seems to not remember that this hint has been given to it when initializing
+    // HotSpotCompiledCodeStream object with a thread returned by JavaThread::current(),
+    // therefore 2nd hint is needed.
+    __builtin_unreachable();
+  }
+#endif
   HandleMark hm(thread);
   int locs_buffer_size = _sites_count * (relocInfo::length_limit + sizeof(relocInfo));
 
diff --git a/src/hotspot/share/runtime/javaThread.hpp b/src/hotspot/share/runtime/javaThread.hpp
index af46492622d5d..a85521b5057f3 100644
--- a/src/hotspot/share/runtime/javaThread.hpp
+++ b/src/hotspot/share/runtime/javaThread.hpp
@@ -1067,7 +1067,16 @@ class JavaThread: public Thread {
  public:
   // Returns the running thread as a JavaThread
   static JavaThread* current() {
-    return JavaThread::cast(Thread::current());
+    auto result = JavaThread::cast(Thread::current());
+#if defined(__GNUC__) && !defined(__clang__) && !defined(PRODUCT)
+  if (result == nullptr) {
+    // This is to prevent --stringop-overflow warning from GCC on linux/fastdebug.
+    // GCC does believe that JavaThread::current() can return nullptr,
+    // though it cannot.
+    __builtin_unreachable();
+  }
+#endif
+    return result;
   }
 
   // Returns the current thread as a JavaThread, or nullptr if not attached